Add Outline to the Edge of Faces of an Object
The Wireframe Modifier can do what you are asking. Note that it will add some extra geometry, so that may or may not be an option for some use cases. 

Under the options for the modifier, you will want to uncheck replace original, and change the material offset to 1. 



Add two materials to your object, the material in slot 2 will be the material for the wireframe. If needed, you can change the material offset to 2 or 3, and the material slot for the wireframe will go to 3 or 4, and so on. 

This is how the material slots look for Suzanne below:



And the result: